PT - JOURNAL ARTICLE AU - Zheng, Zhihao AU - Lauritzen, J. Scott AU - Perlman, Eric AU - Robinson, Camenzind G. AU - Nichols, Matthew AU - Milkie, Daniel AU - Torrens, Omar AU - Price, John AU - Fisher, Corey B. AU - Sharifi, Nadiya AU - Calle-Schuler, Steven A. AU - Kmecova, Lucia AU - Ali, Iqbal J. AU - Karsh, Bill AU - Trautman, Eric T. AU - Bogovic, John AU - Hanslovsky, Philipp AU - Jefferis, Gregory S. X. E. AU - Kazhdan, Michael AU - Khairy, Khaled AU - Saalfeld, Stephan AU - Fetter, Richard D. AU - Bock, Davi D. TI - A complete electron microscopy volume of the brain of adult <em>Drosophila melanogaster</em> AID - 10.1101/140905 DP - 2017 Jan 01 TA - bioRxiv PG - 140905 4099 - http://biorxiv.org/content/early/2017/06/13/140905.short 4100 - http://biorxiv.org/content/early/2017/06/13/140905.full AB - Drosophila melanogaster has a rich repertoire of innate and learned behaviors. Its 100,000–neuron brain is a large but tractable target for comprehensive neural circuit mapping. Only electron microscopy (EM) enables complete, unbiased mapping of synaptic connectivity; however, the fly brain is too large for conventional EM. We developed a custom high-throughput EM platform and imaged the entire brain of an adult female fly. We validated the dataset by tracing brain-spanning circuitry involving the mushroom body (MB), intensively studied for its role in learning. Here we describe the complete set of olfactory inputs to the MB; find a new cell type providing driving input to Kenyon cells (the intrinsic MB neurons); identify neurons postsynaptic to Kenyon cell dendrites; and find that axonal arbors providing input to the MB calyx are more tightly clustered than previously indicated by light-level data. This freely available EM dataset will significantly accelerate Drosophila neuroscience.- A complete adult fruit fly brain was imaged, using electron microscopy (EM)- The EM volume enables brain-spanning mapping of neuronal circuits at the synaptic level- Olfactory projection neurons cluster more tightly in mushroom body calyx than expected from light-level data- The primary postsynaptic targets of Kenyon cells (KCs) in the MB are other KCs, as well as the anterior paired lateral (APL) neuron- A newly discovered cell type, MB-CP2, integrates input from several sensory modalities and provides microglomerular input to KCs in MB calyx- A software pipeline was created in which EM-traced skeletons can be searched for within existing large-scale light microscopy (LM) databases of neuronal morphology, facilitating cell type identification and discovery of relevant genetic driver lines